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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2011 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: AsyncInputStream.html 689 2013-06-28 19:22:16Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.dellroad.stuff.io;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import java.io.IOException;<a name="line.10"></a>
<span class="sourceLineNo">011</span>import java.io.InputStream;<a name="line.11"></a>
<span class="sourceLineNo">012</span><a name="line.12"></a>
<span class="sourceLineNo">013</span>import org.slf4j.Logger;<a name="line.13"></a>
<span class="sourceLineNo">014</span>import org.slf4j.LoggerFactory;<a name="line.14"></a>
<span class="sourceLineNo">015</span><a name="line.15"></a>
<span class="sourceLineNo">016</span>/**<a name="line.16"></a>
<span class="sourceLineNo">017</span> * Performs asynchonous reads on an {@link InputStream} and notifies of input events.<a name="line.17"></a>
<span class="sourceLineNo">018</span> *<a name="line.18"></a>
<span class="sourceLineNo">019</span> * &lt;p&gt;<a name="line.19"></a>
<span class="sourceLineNo">020</span> * Reads are performed in a dedicated background thread, from which the configured listener is notified.<a name="line.20"></a>
<span class="sourceLineNo">021</span> * The background thread runs until this instance is {@linkplain #close closed}, EOF or an exception is detected<a name="line.21"></a>
<span class="sourceLineNo">022</span> * on the input, or a listener callback method throws an exception. A null listener may be supplied; in which case<a name="line.22"></a>
<span class="sourceLineNo">023</span> * this class will just sink the {@link InputStream}.<a name="line.23"></a>
<span class="sourceLineNo">024</span> * &lt;/p&gt;<a name="line.24"></a>
<span class="sourceLineNo">025</span> *<a name="line.25"></a>
<span class="sourceLineNo">026</span> * &lt;p&gt;<a name="line.26"></a>
<span class="sourceLineNo">027</span> * Instances of this class are thread-safe. The {@link #close} method may be safely invoked re-entrantly from the<a name="line.27"></a>
<span class="sourceLineNo">028</span> * listener callback methods.<a name="line.28"></a>
<span class="sourceLineNo">029</span> * &lt;/p&gt;<a name="line.29"></a>
<span class="sourceLineNo">030</span> */<a name="line.30"></a>
<span class="sourceLineNo">031</span>public class AsyncInputStream {<a name="line.31"></a>
<span class="sourceLineNo">032</span><a name="line.32"></a>
<span class="sourceLineNo">033</span>    private static final int BUFFER_SIZE = 4096;<a name="line.33"></a>
<span class="sourceLineNo">034</span><a name="line.34"></a>
<span class="sourceLineNo">035</span>    protected final Logger log = LoggerFactory.getLogger(getClass());<a name="line.35"></a>
<span class="sourceLineNo">036</span><a name="line.36"></a>
<span class="sourceLineNo">037</span>    private final InputStream input;<a name="line.37"></a>
<span class="sourceLineNo">038</span>    private final String name;<a name="line.38"></a>
<span class="sourceLineNo">039</span>    private final Listener listener;<a name="line.39"></a>
<span class="sourceLineNo">040</span><a name="line.40"></a>
<span class="sourceLineNo">041</span>    private boolean closed;                     // this instance has been close()'d<a name="line.41"></a>
<span class="sourceLineNo">042</span><a name="line.42"></a>
<span class="sourceLineNo">043</span>    /**<a name="line.43"></a>
<span class="sourceLineNo">044</span>     * Constructor.<a name="line.44"></a>
<span class="sourceLineNo">045</span>     *<a name="line.45"></a>
<span class="sourceLineNo">046</span>     * &lt;p&gt;<a name="line.46"></a>
<span class="sourceLineNo">047</span>     * If {@code listener} is null, this instance effectively reads and discards all of the input in a background thread.<a name="line.47"></a>
<span class="sourceLineNo">048</span>     * &lt;/p&gt;<a name="line.48"></a>
<span class="sourceLineNo">049</span>     *<a name="line.49"></a>
<span class="sourceLineNo">050</span>     * @param input     underlying input stream<a name="line.50"></a>
<span class="sourceLineNo">051</span>     * @param name      name for this instance; used to create the name of the background thread<a name="line.51"></a>
<span class="sourceLineNo">052</span>     * @param listener  callback object for input events, or null for none<a name="line.52"></a>
<span class="sourceLineNo">053</span>     * @throws IllegalArgumentException if any parameter is null<a name="line.53"></a>
<span class="sourceLineNo">054</span>     */<a name="line.54"></a>
<span class="sourceLineNo">055</span>    public AsyncInputStream(InputStream input, String name, Listener listener) {<a name="line.55"></a>
<span class="sourceLineNo">056</span>        if (input == null)<a name="line.56"></a>
<span class="sourceLineNo">057</span>            throw new IllegalArgumentException("null input");<a name="line.57"></a>
<span class="sourceLineNo">058</span>        if (name == null)<a name="line.58"></a>
<span class="sourceLineNo">059</span>            throw new IllegalArgumentException("name input");<a name="line.59"></a>
<span class="sourceLineNo">060</span>        this.input = input;<a name="line.60"></a>
<span class="sourceLineNo">061</span>        this.name = name;<a name="line.61"></a>
<span class="sourceLineNo">062</span>        this.listener = listener;<a name="line.62"></a>
<span class="sourceLineNo">063</span>        new Thread(this.name) {<a name="line.63"></a>
<span class="sourceLineNo">064</span>            @Override<a name="line.64"></a>
<span class="sourceLineNo">065</span>            public void run() {<a name="line.65"></a>
<span class="sourceLineNo">066</span>                AsyncInputStream.this.threadMain();<a name="line.66"></a>
<span class="sourceLineNo">067</span>            }<a name="line.67"></a>
<span class="sourceLineNo">068</span>        }.start();<a name="line.68"></a>
<span class="sourceLineNo">069</span>    }<a name="line.69"></a>
<span class="sourceLineNo">070</span><a name="line.70"></a>
<span class="sourceLineNo">071</span>    /**<a name="line.71"></a>
<span class="sourceLineNo">072</span>     * Close this instance.<a name="line.72"></a>
<span class="sourceLineNo">073</span>     *<a name="line.73"></a>
<span class="sourceLineNo">074</span>     * &lt;p&gt;<a name="line.74"></a>
<span class="sourceLineNo">075</span>     * Does nothing if already closed.<a name="line.75"></a>
<span class="sourceLineNo">076</span>     */<a name="line.76"></a>
<span class="sourceLineNo">077</span>    public synchronized void close() {<a name="line.77"></a>
<span class="sourceLineNo">078</span>        if (this.closed)<a name="line.78"></a>
<span class="sourceLineNo">079</span>            return;<a name="line.79"></a>
<span class="sourceLineNo">080</span>        try {<a name="line.80"></a>
<span class="sourceLineNo">081</span>            this.input.close();<a name="line.81"></a>
<span class="sourceLineNo">082</span>        } catch (IOException e) {<a name="line.82"></a>
<span class="sourceLineNo">083</span>            // ignore; we assume main thread will awake in any case<a name="line.83"></a>
<span class="sourceLineNo">084</span>        }<a name="line.84"></a>
<span class="sourceLineNo">085</span>        this.closed = true;<a name="line.85"></a>
<span class="sourceLineNo">086</span>    }<a name="line.86"></a>
<span class="sourceLineNo">087</span><a name="line.87"></a>
<span class="sourceLineNo">088</span>    /**<a name="line.88"></a>
<span class="sourceLineNo">089</span>     * Writer thread main entry point.<a name="line.89"></a>
<span class="sourceLineNo">090</span>     */<a name="line.90"></a>
<span class="sourceLineNo">091</span>    private void threadMain() {<a name="line.91"></a>
<span class="sourceLineNo">092</span>        try {<a name="line.92"></a>
<span class="sourceLineNo">093</span>            this.runLoop();<a name="line.93"></a>
<span class="sourceLineNo">094</span>        } catch (Throwable t) {<a name="line.94"></a>
<span class="sourceLineNo">095</span>            synchronized (this) {<a name="line.95"></a>
<span class="sourceLineNo">096</span>                if (this.closed)<a name="line.96"></a>
<span class="sourceLineNo">097</span>                    return;<a name="line.97"></a>
<span class="sourceLineNo">098</span>            }<a name="line.98"></a>
<span class="sourceLineNo">099</span>            try {<a name="line.99"></a>
<span class="sourceLineNo">100</span>                if (this.listener != null)<a name="line.100"></a>
<span class="sourceLineNo">101</span>                    this.listener.handleException(t);<a name="line.101"></a>
<span class="sourceLineNo">102</span>            } catch (Exception e) {<a name="line.102"></a>
<span class="sourceLineNo">103</span>                this.log.error(this.name + ": caught unexpected exception", e);<a name="line.103"></a>
<span class="sourceLineNo">104</span>            }<a name="line.104"></a>
<span class="sourceLineNo">105</span>        }<a name="line.105"></a>
<span class="sourceLineNo">106</span>    }<a name="line.106"></a>
<span class="sourceLineNo">107</span><a name="line.107"></a>
<span class="sourceLineNo">108</span>    /**<a name="line.108"></a>
<span class="sourceLineNo">109</span>     * Async reader thread main loop.<a name="line.109"></a>
<span class="sourceLineNo">110</span>     */<a name="line.110"></a>
<span class="sourceLineNo">111</span>    private void runLoop() throws IOException {<a name="line.111"></a>
<span class="sourceLineNo">112</span>        byte[] buf = new byte[BUFFER_SIZE];<a name="line.112"></a>
<span class="sourceLineNo">113</span>        while (true) {<a name="line.113"></a>
<span class="sourceLineNo">114</span>            int r = this.input.read(buf);<a name="line.114"></a>
<span class="sourceLineNo">115</span>            if (r == -1) {<a name="line.115"></a>
<span class="sourceLineNo">116</span>                if (this.listener != null)<a name="line.116"></a>
<span class="sourceLineNo">117</span>                    this.listener.handleEOF();<a name="line.117"></a>
<span class="sourceLineNo">118</span>                break;<a name="line.118"></a>
<span class="sourceLineNo">119</span>            }<a name="line.119"></a>
<span class="sourceLineNo">120</span>            if (this.listener != null)<a name="line.120"></a>
<span class="sourceLineNo">121</span>                this.listener.handleInput(buf, 0, r);<a name="line.121"></a>
<span class="sourceLineNo">122</span>        }<a name="line.122"></a>
<span class="sourceLineNo">123</span>    }<a name="line.123"></a>
<span class="sourceLineNo">124</span><a name="line.124"></a>
<span class="sourceLineNo">125</span>    /**<a name="line.125"></a>
<span class="sourceLineNo">126</span>     * Callback interface required by {@link AsyncInputStream}.<a name="line.126"></a>
<span class="sourceLineNo">127</span>     */<a name="line.127"></a>
<span class="sourceLineNo">128</span>    public interface Listener {<a name="line.128"></a>
<span class="sourceLineNo">129</span><a name="line.129"></a>
<span class="sourceLineNo">130</span>        /**<a name="line.130"></a>
<span class="sourceLineNo">131</span>         * Handle new data read from the underlying input.<a name="line.131"></a>
<span class="sourceLineNo">132</span>         * This method must not write to buffer bytes outside of the defined region.<a name="line.132"></a>
<span class="sourceLineNo">133</span>         *<a name="line.133"></a>
<span class="sourceLineNo">134</span>         * @param buf data buffer<a name="line.134"></a>
<span class="sourceLineNo">135</span>         * @param off starting offset of data in buffer<a name="line.135"></a>
<span class="sourceLineNo">136</span>         * @param len number of bytes of data<a name="line.136"></a>
<span class="sourceLineNo">137</span>         */<a name="line.137"></a>
<span class="sourceLineNo">138</span>        void handleInput(byte[] buf, int off, int len);<a name="line.138"></a>
<span class="sourceLineNo">139</span><a name="line.139"></a>
<span class="sourceLineNo">140</span>        /**<a name="line.140"></a>
<span class="sourceLineNo">141</span>         * Handle an exception detected on the underlying input.<a name="line.141"></a>
<span class="sourceLineNo">142</span>         * No further events will be delivered.<a name="line.142"></a>
<span class="sourceLineNo">143</span>         *<a name="line.143"></a>
<span class="sourceLineNo">144</span>         * &lt;p&gt;<a name="line.144"></a>
<span class="sourceLineNo">145</span>         * Typically the assocaited {@link AsyncInputStream} will be closed in this callback.<a name="line.145"></a>
<span class="sourceLineNo">146</span>         *<a name="line.146"></a>
<span class="sourceLineNo">147</span>         * @param e the exception received (usually {@link IOException} but could also be any other {@link RuntimeException})<a name="line.147"></a>
<span class="sourceLineNo">148</span>         */<a name="line.148"></a>
<span class="sourceLineNo">149</span>        void handleException(Throwable e);<a name="line.149"></a>
<span class="sourceLineNo">150</span><a name="line.150"></a>
<span class="sourceLineNo">151</span>        /**<a name="line.151"></a>
<span class="sourceLineNo">152</span>         * Handle end-of-file detected on the underlying input.<a name="line.152"></a>
<span class="sourceLineNo">153</span>         * No further events will be delivered.<a name="line.153"></a>
<span class="sourceLineNo">154</span>         *<a name="line.154"></a>
<span class="sourceLineNo">155</span>         * &lt;p&gt;<a name="line.155"></a>
<span class="sourceLineNo">156</span>         * Typically the assocaited {@link AsyncInputStream} will be closed in this callback.<a name="line.156"></a>
<span class="sourceLineNo">157</span>         */<a name="line.157"></a>
<span class="sourceLineNo">158</span>        void handleEOF();<a name="line.158"></a>
<span class="sourceLineNo">159</span>    }<a name="line.159"></a>
<span class="sourceLineNo">160</span>}<a name="line.160"></a>
<span class="sourceLineNo">161</span><a name="line.161"></a>




























































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